Ever stricter statutory requirements in terms of admissible emissions of pollutants by motor vehicles in which internal combustion engines are arranged make it necessary to keep the emissions of pollutants as low as possible during operation of the internal combustion engine. This can occur, on the one hand, by virtue of the fact that there is a reduction in the emissions of pollutants which are produced during the combustion of the air/fuel mixture in the respective cylinder of the internal combustion engine. On the other hand, exhaust gas post-treatment systems are in use in internal combustion engines, which exhaust gas post-treatment systems convert the emissions of pollutants which are generated during the combustion process of the air/fuel mixture in the respective cylinders into harmless substances. For this purpose, exhaust gas catalytic converters are used which convert carbon monoxide, hydrocarbons and nitrogen oxides into harmless substances. Both the targeted influencing of the generation of the emissions of pollutants during the combustion and the conversion of the components of the pollutants with a high degree of efficiency by the exhaust gas catalytic converter require a very precisely set air/fuel ratio in the respective cylinder.
In this connection, binary lambda probes are used by way of example. The measurement signal of the binary lambda probe has a magnitude of high gradient, when exhaust gas which results from a mixture of air and fuel before the combustion flows past it, when the mixture varies in a very narrow range around a stoichiometric mixture. In the case of exhaust gas which results from a mixture of air and fuel before the combustion and lies outside the narrow window around the stoichiometric mixture, the measurement signal has a very flat profile.
DE 10 2006 014 697 A1 discloses a lambda probe for motor vehicles comprising at least one reference electrode, which is arranged in a solid electrolyte, and an exhaust gas electrode, which is exposed to the exhaust gas and is provided with a porous ceramic coating. Also provided is a circuit arrangement by means of which an oxygen stream which flows to the exhaust gas electrode can be generated between the reference electrode and the exhaust gas electrode, the size of said oxygen stream being matched to the gas streams which diffuse through the porous coating such that a targeted lambda step change shift takes place.